1. Field
Embodiments of the inventive concepts relate to semiconductor devices having a vertical transistor and a non-vertical transistor and methods of forming the same.
2. Description of Related Art
A vast amount of research has been conducted on various methods for embodying low-power semiconductor devices. With the growing tendency for MOSFETs to have channel lengths of about 100 nm or less, the fabrication of semiconductor devices having both a high driving current and a low off-leakage current has become increasingly difficult due to a phenomenon known in the industry as the short-channel effect. To overcome these limitations, fabrication techniques have been employed whereby devices having different threshold voltages are formed on the same semiconductor substrate by controlling the doping profile of a channel region. However, as the operating voltage of devices becomes about 1 V or lower, the leakage current of a low threshold voltage (VT) device may greatly increase, leading to unreliable and inefficient operation.